Memory Arrays, and Methods of Forming Memory Arrays

ABSTRACT

Some embodiments include a method of forming an assembly (e.g., a memory array). A first opening is formed through a stack of alternating first and second levels. The first levels contain silicon nitride, and the second levels contain silicon dioxide. Some of the silicon dioxide of the second levels is replaced with memory cell structures. The memory cell structures include charge-storage regions adjacent charge-blocking regions. Tunneling material is formed within the first opening, and channel material is formed adjacent the tunneling material. A second opening is formed through the stack. The second opening extends through remaining portions of the silicon dioxide, and through the silicon nitride. The remaining portions of the silicon dioxide are removed to form cavities. Conductive regions are formed within the cavities. The silicon nitride is removed to form voids between the conductive regions. Some embodiments include memory arrays.

RELATED PATENT DATA

This patent resulted from a divisional of U.S. patent application Ser.No. 15/948,639 filed Apr. 9, 2018, which claims priority to U.S.Provisional application Ser. No. 62/610,657, which was filed Dec. 27,2017, each of which is hereby incorporated by reference herein.

TECHNICAL FIELD

Memory arrays (e.g., NAND memory arrays), and methods of forming memoryarrays.

BACKGROUND

Memory provides data storage for electronic systems. Flash memory is onetype of memory, and has numerous uses in modern computers and devices.For instance, modern personal computers may have BIOS stored on a flashmemory chip. As another example, it is becoming increasingly common forcomputers and other devices to utilize flash memory in solid statedrives to replace conventional hard drives. As yet another example,flash memory is popular in wireless electronic devices because itenables manufacturers to support new communication protocols as theybecome standardized, and to provide the ability to remotely upgrade thedevices for enhanced features.

NAND may be a basic architecture of flash memory, and may be configuredto comprise vertically-stacked memory cells.

Before describing NAND specifically, it may be helpful to more generallydescribe the relationship of a memory array within an integratedarrangement. FIG. 1 shows a block diagram of a prior art device 100which includes a memory array 102 having a plurality of memory cells 103arranged in rows and columns along with access lines 104 (e.g.,wordlines to conduct signals WL0 through WLm) and first data lines 106(e.g., bitlines to conduct signals BL0 through BLn). Access lines 104and first data lines 106 may be used to transfer information to and fromthe memory cells 103. A row decoder 107 and a column decoder 108 decodeaddress signals AO through AX on address lines 109 to determine whichones of the memory cells 103 are to be accessed. A sense amplifiercircuit 115 operates to determine the values of information read fromthe memory cells 103. An I/O circuit 117 transfers values of informationbetween the memory array 102 and input/output (I/O) lines 105. SignalsDQO through DQN on the I/O lines 105 can represent values of informationread from or to be written into the memory cells 103. Other devices cancommunicate with the device 100 through the I/O lines 105, the addresslines 109, or the control lines 120. A memory control unit 118 is usedto control memory operations to be performed on the memory cells 103,and utilizes signals on the control lines 120. The device 100 canreceive supply voltage signals Vcc and Vss on a first supply line 130and a second supply line 132, respectively. The device 100 includes aselect circuit 140 and an input/output (I/O) circuit 117. The selectcircuit 140 can respond, via the I/O circuit 117, to signals CSEL1through CSELn to select signals on the first data lines 106 and thesecond data lines 113 that can represent the values of information to beread from or to be programmed into the memory cells 103. The columndecoder 108 can selectively activate the CSEL1 through CSELn signalsbased on the AO through AX address signals on the address lines 109. Theselect circuit 140 can select the signals on the first data lines 106and the second data lines 113 to provide communication between thememory array 102 and the I/O circuit 117 during read and programmingoperations.

The memory array 102 of FIG. 1 may be a NAND memory array, and FIG. 2shows a block diagram of a three-dimensional NAND memory device 200which may be utilized for the memory array 102 of FIG. 1. The device 200comprises a plurality of strings of charge-storage devices. In a firstdirection (Z-Z′), each string of charge-storage devices may comprise,for example, thirty-two charge-storage devices stacked over one anotherwith each charge-storage device corresponding to one of, for example,thirty-two tiers (e.g., Tier0-Tier31). The charge-storage devices of arespective string may share a common channel region, such as one formedin a respective pillar of semiconductor material (e.g., polysilicon)about which the string of charge-storage devices is formed. In a seconddirection (X-X′), each first group of, for example, sixteen first groupsof the plurality of strings may comprise, for example, eight stringssharing a plurality (e.g., thirty-two) of access lines (i.e., “globalcontrol gate (CG) lines”, also known as wordlines, WLs). Each of theaccess lines may couple the charge-storage devices within a tier. Thecharge-storage devices coupled by the same access line (and thuscorresponding to the same tier) may be logically grouped into, forexample, two pages, such as P0/P32, P1/P33, P2/P34 and so on, when eachcharge-storage device comprises a cell capable of storing two bits ofinformation. In a third direction (Y-Y′), each second group of, forexample, eight second groups of the plurality of strings, may comprisesixteen strings coupled by a corresponding one of eight data lines. Thesize of a memory block may comprise 1,024 pages and total about 16 MB(e.g., 16 WLs×32 tiers×2 bits=1,024 pages/block, block size=1,024pages×16 KB/page=16 MB). The number of the strings, tiers, access lines,data lines, first groups, second groups and/or pages may be greater orsmaller than those shown in FIG. 2.

FIG. 3 shows a cross-sectional view of a memory block 300 of the 3D NANDmemory device 200 of FIG. 2 in an X-X′ direction, including fifteenstrings of charge-storage devices in one of the sixteen first groups ofstrings described with respect to FIG. 2. The plurality of strings ofthe memory block 300 may be grouped into a plurality of subsets 310,320, 330 (e.g., tile columns), such as tile column_(I), tile column_(j)and tile column_(K), with each subset (e.g., tile column) comprising a“partial block” of the memory block 300. A global drain-side select gate(SGD) line 340 may be coupled to the SGDs of the plurality of strings.For example, the global SGD line 340 may be coupled to a plurality(e.g., three) of sub-SGD lines 342, 344, 346 with each sub-SGD linecorresponding to a respective subset (e.g., tile column), via acorresponding one of a plurality (e.g., three) of sub-SGD drivers 332,334, 336. Each of the sub-SGD drivers 332, 334, 336 may concurrentlycouple or cut off the SGDs of the strings of a corresponding partialblock (e.g., tile column) independently of those of other partialblocks. A global source-side select gate (SGS) line 360 may be coupledto the SGSs of the plurality of strings. For example, the global SGSline 360 may be coupled to a plurality of sub-SGS lines 362, 364, 366with each sub-SGS line corresponding to the respective subset (e.g.,tile column), via a corresponding one of a plurality of sub-SGS drivers322, 324, 326. Each of the sub-SGS drivers 322, 324, 326 mayconcurrently couple or cut off the SGSs of the strings of acorresponding partial block (e.g., tile column) independently of thoseof other partial blocks. A global access line (e.g., a global CG line)350 may couple the charge-storage devices corresponding to therespective tier of each of the plurality of strings. Each global CG line(e.g., the global CG line 350) may be coupled to a plurality ofsub-access lines (e.g., sub-CG lines) 352, 354, 356 via a correspondingone of a plurality of sub-string drivers 312, 314 and 316. Each of thesub-string drivers may concurrently couple or cut off the charge-storagedevices corresponding to the respective partial block and/or tierindependently of those of other partial blocks and/or other tiers. Thecharge-storage devices corresponding to the respective subset (e.g.,partial block) and the respective tier may comprise a “partial tier”(e.g., a single “tile”) of charge-storage devices. The stringscorresponding to the respective subset (e.g., partial block) may becoupled to a corresponding one of sub-sources 372, 374 and 376 (e.g.,“tile source”) with each sub-source being coupled to a respective powersource.

The NAND memory device 200 is alternatively described with reference toa schematic illustration of FIG. 4.

The memory array 200 includes wordlines 202 ₁ to 202 _(N), and bitlines228 ₁ to 228 _(M).

The memory array 200 also includes NAND strings 206 ₁ to 206 _(M). EachNAND string includes charge-storage transistors 208 ₁ to 208 _(N). Thecharge-storage transistors may use floating gate material (e.g.,polysilicon) to store charge, or may use charge-trapping material (suchas, for example, silicon nitride, metallic nanodots, etc.) to storecharge.

The charge-storage transistors 208 are located at intersections ofwordlines 202 and strings 206. The charge-storage transistors 208represent non-volatile memory cells for storage of data. Thecharge-storage transistors 208 of each NAND string 206 are connected inseries source-to-drain between a source-select device (e.g., source-sideselect gate, SGS) 210 and a drain-select device (e.g., drain-side selectgate, SGD) 212. Each source-select device 210 is located at anintersection of a string 206 and a source-select line 214, while eachdrain-select device 212 is located at an intersection of a string 206and a drain-select line 215. The select devices 210 and 212 may be anysuitable access devices, and are generically illustrated with boxes inFIG. 1.

A source of each source-select device 210 is connected to a commonsource line 216. The drain of each source-select device 210 is connectedto the source of the first charge-storage transistor 208 of thecorresponding NAND string 206. For example, the drain of source-selectdevice 2101 is connected to the source of charge-storage transistor 208₁ of the corresponding NAND string 206 ₁. The source-select devices 210are connected to source-select line 214.

The drain of each drain-select device 212 is connected to a bitline(i.e., digit line) 228 at a drain contact. For example, the drain ofdrain-select device 212 ₁ is connected to the bitline 228 ₁. The sourceof each drain-select device 212 is connected to the drain of the lastcharge-storage transistor 208 of the corresponding NAND string 206. Forexample, the source of drain-select device 212 ₁ is connected to thedrain of charge-storage transistor 208 _(N) of the corresponding NANDstring 206 ₁.

The charge-storage transistors 208 include a source 230, a drain 232, acharge-storage region 234, and a control gate 236. The charge-storagetransistors 208 have their control gates 236 coupled to a wordline 202.A column of the charge-storage transistors 208 are those transistorswithin a NAND string 206 coupled to a given bitline 228. A row of thecharge-storage transistors 208 are those transistors commonly coupled toa given wordline 202.

It would be desirable to develop improved memory cell designs, improvedmemory array architecture (e.g., improved NAND architecture), andmethods for fabricating the improved memory cells and improved memoryarray architectures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of a prior art memory device having amemory array with memory cells.

FIG. 2 shows a schematic diagram of the prior art memory array of FIG. 1in the form of a 3D NAND memory device.

FIG. 3 shows a cross-sectional view of the prior art 3D NAND memorydevice of FIG. 2 in an X-X′ direction.

FIG. 4 is a schematic diagram of a prior art NAND memory array.

FIGS. 5-24 are diagrammatic cross-sectional views of regions of aconstruction at example process steps of an example method forfabricating an example assembly.

FIGS. 6A and 19A are diagrammatic top views along the lines A-A of FIGS.6 and 19, respectively.

FIGS. 25 and 26 are diagrammatic cross-sectional views of regions of theconstruction of FIG. 22 at example process steps that may follow theexample process stage of FIG. 22 in an example method different fromthat described with reference to FIGS. 23 and 24.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Some embodiments include memory arrays having low-density silicondioxide wrapping around ends of wordline levels. Some embodimentsinclude memory cells having charge-blocking regions which comprisesilicon oxynitride. The charge-blocking regions may additionallycomprise silicon dioxide. Some embodiments include memory arrays (e.g.,NAND memory arrays) having vertically-stacked memory cells, and havingvoids between vertically-adjacent memory cells. Some embodiments includemethods of forming memory cells, and memory arrays. Example methods aredescribed with reference to FIGS. 5-26, and example architectures aredescribed with reference to FIGS. 24 and 26.

Referring to FIG. 5, a construction (i.e., assembly, architecture, etc.)10 includes a stack 12 of alternating first and second levels 14 and 16.The first levels 14 comprise first material 18, and the second levels 16comprise second material 20. The first and second materials 18 and 20may be any suitable materials. In some embodiments, the first material18 may comprise, consist essentially of, or consist of silicon nitride;and the second material 20 may comprise, consist essentially of, orconsist of silicon dioxide.

The levels 14 and 16 may be of any suitable thicknesses; and may be thesame thickness as one another, or different thicknesses relative to oneanother. In some embodiments, the levels 14 and 16 may have verticalthicknesses within a range of from about 10 nanometers (nm) to about 400nm. In some embodiments, the second levels 16 may be thicker than thefirst levels 14. For instance, in some embodiments the second levels 16may have thicknesses within a range of from about 20 nm to about 40 nm,and the first levels 14 may have thicknesses within a range of fromabout 15 nm to about 30 nm.

Some of the material 20 of the second levels 16 is ultimately replacedwith conductive material of memory cell gates. Accordingly, the levels16 may ultimately correspond to memory cell levels of a NANDconfiguration. The NAND configuration will include strings of memorycells (i.e., NAND strings), with the number of memory cells in thestrings being determined by the number of vertically-stacked levels 16.The NAND strings may comprise any suitable number of memory cell levels.For instance, the NAND strings may have 8 memory cell levels, 16 andmemory cell levels, 32 memory cell levels, 64 memory cell levels, 512memory cell levels, 1024 memory cell levels, etc. A portion or portionsof the cell levels may be used as select gate(s). The vertical stack 12is shown to extend outwardly beyond the illustrated region of the stackto indicate that there may be more vertically-stacked levels than thosespecifically illustrated in the diagram of FIG. 5.

The stack 12 is shown to be supported over a base 22. The base 22 maycomprise semiconductor material; and may, for example, comprise, consistessentially of, or consist of monocrystalline silicon. The base 22 maybe referred to as a semiconductor substrate. The term “semiconductorsubstrate” means any construction comprising semiconductive material,including, but not limited to, bulk semiconductive materials such as asemiconductive wafer (either alone or in assemblies comprising othermaterials), and semiconductive material layers (either alone or inassemblies comprising other materials). The term “substrate” refers toany supporting structure, including, but not limited to, thesemiconductor substrates described above. In some applications, the base22 may correspond to a semiconductor substrate containing one or morematerials associated with integrated circuit fabrication. Such materialsmay include, for example, one or more of refractory metal materials,barrier materials, diffusion materials, insulator materials, etc.

A space is provided between the stack 12 and the base 22 to indicatethat other components and materials may be provided between the stack 12and the base 22. Such other components and materials may compriseadditional levels of the stack, a source line level, source-side selectgates (SGSs), etc.

Referring to FIG. 6, an opening 24 is formed through the stack 12. Theopening is ultimately utilized for fabricating channel material pillarsassociated with vertically-stacked memory cells of a memory array, andin some embodiments may be referred to as a pillar opening. The opening24 may have any suitable configuration when viewed from above; and insome example embodiments may be circular, elliptical, polygonal, etc.FIG. 6A shows a top view of a portion of the top level 16 of theillustrated region of construction 10, and illustrates an exampleconfiguration in which the opening 24 is circular-shaped when viewedfrom above. In some embodiments, the opening 24 may be referred to as afirst opening in order to distinguish it from other openings formed atlater process stages. The pillar opening 24 may be representative of alarge plurality of substantially identical openings formed across thebase 22 at the processing stage of FIG. 6 (with the term “substantiallyidentical” meaning identical to within reasonable tolerances offabrication and measurement).

Referring to FIG. 7, the material 18 of the first levels 14 is recessedalong the opening 24 to form gaps (i.e., cavities) 26. The gaps 26 maybe referred to as first gaps to distinguish them from other gaps formedat subsequent process stages.

In some embodiments, the material 18 of the first levels 14 maycomprise, consist essentially of, or consist of silicon nitride; and thematerial 20 of the second levels 16 may comprise, consist essentiallyof, or consist of silicon dioxide. In such embodiments, the material 18may be selectively etched relative to the material 20 utilizingphosphoric acid. The term “selective etching” means that a material isremoved faster than another material, and includes, but is not limitedto, etching processes which are 100% selective for one material relativeto another.

The first gaps 26 are vertically between segments 28 of the material 20of the second levels 16.

The first gaps extend into the first levels 14 to a depth D1. Such depthmay be any suitable depth, and in some embodiments will be within arange of from about 10 nm to about 20 nm.

Referring to FIG. 8, spacing structures 30 are formed within the firstgaps 26. The spacing structures 30 comprise material 32. Such materialmay comprise any suitable composition(s); and in some embodiments maycomprise silicon. For instance, in some example embodiments, thematerial 32 may comprise, consist essentially of, or consist ofpolycrystalline silicon. The spacing structures 30 comprise outer edges29 along the opening 24.

The material 32 may be formed within the gaps 26 with any suitableprocessing. For instance, in some embodiments material 32 may bedeposited through the opening 24 and into the gaps 26; resulting in thegaps 26 being filled with the material 32 and the opening 24 being atleast partially filled with the material 32. Subsequently, an etch maybe utilized to remove excess material 32 from within the opening 24,while leaving the material 32 within the gaps 26. The etch may utilizeany suitable etchant and etching conditions. In some exampleembodiments, the etch will utilize tetramethylammonium hydroxide (TMAH).

Referring to FIG. 9, the material 20 of the second levels 16 is recessedalong the opening 24 to form second gaps 34. In some embodiments, thematerial 20 of the second levels 16 may comprise, consist essentiallyof, or consist of silicon dioxide; and the material 32 of the spacingstructures 30 may comprise, consist essentially of, or consist ofpolycrystalline silicon. In such embodiments, the material 20 may beselectively etched relative to the material 32 utilizing a bufferedoxide etch (e.g., an etch utilizing a hydrofluoric acid and a bufferingagent, such as ammonium fluoride). The gaps 34 are vertically betweensegments 36 of the spacing structures 30. Remaining portions of thesecond material 20 are behind the gaps 34 (and in some embodiments maybe referred to as being along the gaps 34).

The second gaps 34 extend into the first levels 14 to a depth D2. Suchdepth may be any suitable depth, and in some embodiments will be withina range of from about 10 nm to about 30 nm.

In some embodiments, the second gaps 34 may be each considered tocomprise an upper periphery (or upper peripheral surface) 31, a lowerperiphery (or lower peripheral surface) 33, and an inner periphery (orinner peripheral surface 35); with the inner periphery extending betweenthe upper periphery and the lower periphery.

In the illustrated embodiment, regions 39 of the first material 18 areexposed along back portions of the second gaps 34. The exposed regionsare along a depth D3 at the back of the second gaps 34. In someembodiments, the depth D3 may be within a range of from about 5angstroms (Å) to about 70 Å. In alternative embodiments, regions of thefirst material 18 are not exposed along the back portions of the secondgaps.

Referring to FIG. 10, a layer of dielectric barrier material 38 isformed to extend conformally along the peripheral surfaces 31, 33 and 35within the gaps 34; and to extend along the outer edges 29 of thespacing structures 30. The dielectric barrier material 38 may compriseany suitable composition(s); and in some embodiments may comprise one ormore high-k materials (with the term high-k meaning a dielectricconstant greater than that of silicon dioxide). Example compositionswhich may be incorporated into the dielectric barrier material arehafnium oxide, zirconium oxide, aluminum oxide, hafnium silicate,zirconium silicate, titanium oxide, gadolinium oxide, niobium oxide,tantalum oxide, etc.

The dielectric barrier material 38 narrows the second gaps 34.

Referring to FIG. 11, a material 40 is formed within the narrowed gaps34. In some embodiments, the material 40 may comprise, consistessentially of, or consist of silicon nitride. The material 40 may beformed in the shown configuration by initially providing a mass of thematerial 40 to at least partially fill the opening 24 (i.e., to extendwithin the gaps 34, and along outer edges 29 of the spacing structures30; with the mass being spaced from the outer edges by the dielectricbarrier material 38), and then removing some of the mass of material 40while leave remaining portions of the material 40 within the gaps 34.

The material 40 at the processing stage of FIG. 11 may be considered tobe configured as segments 42 which are within the gaps 34.Vertically-neighboring segments 42 are vertically-spaced from oneanother by intervening regions 44 which include the spacing structures30.

Referring to FIG. 12, regions of the dielectric material 38 are removedfrom along the outer edges 29 of the spacing structures 30 to exposesuch outer edges along the opening 24. The dielectric material 38remaining at the processing stage of FIG. 12 may be considered to beconfigured as liners 46 extending within the cavities 34, and along theperipheral surfaces 31, 33 and 35 of such cavities.

Referring to FIG. 13, the surfaces within opening 24 are exposed tooxidizing conditions which oxidize the segments 42 (FIG. 12) to formcharge-blocking regions 48, and which also oxidize edges of the spacingstructures 30 (FIG. 11) to form the ledges 50. The oxidizing conditionsmay utilize any suitable chemistry and operational parameters. In someexample embodiments, the oxidizing conditions may comprise anoperational temperature of the oxidizing ambient and/or the oxidizingsurfaces of at least about 700° C. (but not limited to being at leastabout 700°, and may be lower if suitable oxidative conditions achievedesired electrical and/or other properties). The oxidizing conditionsmay, for example, utilize steam (for instance, in situ steam generation(ISSG)) as a source of the oxidant, and/or may utilize plasma togenerate oxidizing species. The plasma may be a so-called “remoteplasma”, meaning that the plasma does not contact the surfaces withinopening 24 which are to be oxidized, but instead only the oxidizingspecies generated by such plasma reach the oxidizing surfaces.

In some embodiments, the material 40 (FIG. 12) of the segments 42 (FIG.12) comprises, consists essentially of, or consist of silicon nitride;and the material 32 (FIG. 12) of the spacing structures 30 (FIG. 12)comprises, consists essentially of, or consists of polycrystallinesilicon. The oxidation may oxidize the silicon nitride 40 to formsilicon oxynitride 54 and silicon dioxide 52; and may oxidize thepolycrystalline silicon 32 to form additional silicon dioxide 52. Insuch embodiments, the charge-blocking regions 48 may comprise thesilicon oxynitride 54 and the silicon dioxide 52 (as shown). Boundariesbetween the materials 52 and 54 are diagrammatically illustrated in FIG.13 with dashed-lines 53 to indicate that the boundary between thematerials 52 and 54 may be an abrupt interface between the siliconoxynitride and the silicon dioxide, or may be a gradient.

In some embodiments, at least portions of the charge-blocking regions 48and/or the ledges 50 may be formed by deposition of suitable material(s)(e.g., silicon dioxide), followed by appropriate etching to achieve adesired shape (such as, for example, shapes analogous to the shapes ofthe charge-blocking regions 48 and ledges 50 shown in FIG. 13).

The charge-blocking regions 48 extend vertically, and have horizontalthicknesses T1. Such horizontal thicknesses may be of any suitabledimension, and in some embodiments may be within a range of from about50 Å to about 150 Å. The silicon oxynitride material 54 of thecharge-blocking regions has a horizontal thickness T2; and the silicondioxide material 52 of the charge-blocking regions has a horizontalthickness T3. In some embodiments, the horizontal thickness T2 will beat least about double the horizontal thickness T3. In some embodiments,the horizontal thickness T2 will be within a range of from about 20 Å toabout 140 Å; and the horizontal thickness T3 will be within a range offrom about 10 Å to about 30 Å. In some embodiments, the horizontalthicknesses T2 and T3 may be referred to as first and second horizontalthicknesses in order to distinguish them from one another.

The oxidation of materials 32 and 40 (FIG. 11) may oxidize thepolycrystalline silicon material 32 much faster than the silicon nitridematerial 40 (for instance, may oxidize the polycrystalline silicon atleast 1.5 times as fast as the silicon nitride, at least twice as fastas the silicon nitride, at least three times as fast as the siliconnitride, etc.). In embodiments in which the oxidation induces much moreexpansion from the silicon dioxide 52 formed from the polycrystallinesilicon 32 than from the silicon oxynitride 54/silicon dioxide 52 formedfrom the silicon nitride material 40, the edges of the tiers 16 alongopening 24 may expand little, if at all, and the edges of the tiers 14along opening 24 may expand substantially (e.g., the expansion due tothe formation of the silicon dioxide 52 from polycrystalline silicon 32material may be at a least about double the expansion due to theformation of the silicon oxynitride 54/silicon dioxide 52 from thesilicon nitride material 40). In some embodiments there may besubstantial expansion along the edges of the tiers 14 along the opening24, and there may be substantially no expansion along the edges of thetiers 16 along the opening 24 (with the term “substantially noexpansion” meaning no expansion to within reasonable tolerances ofdetection). The ledges 50 are shown to be horizontally longer than thecharge-blocking regions 48. Third gaps 56 are along the second levels16, and vertically between the ledges 50.

In the shown embodiment, silicon oxynitride 58 is formed along regionswhere silicon dioxide 52 of ledges 50 is adjacent the silicon nitride 18of levels 14. Dashed-lines 59 are provided to show approximateboundaries between the silicon oxynitride 58 and the silicon nitride 18,and to indicate that such boundaries may be abrupt interfaces, or may begradients. In some embodiments, the ledges 50 may be considered tocomprise front edges 55 along the opening 24, and back edges 57 inopposing relation to the front edges 55; with the back edges 57 beingadjacent the first material 18. The silicon oxynitride 58 is along theback edges 57 of the ledges 50, and may be configured as siliconoxynitride liners 60.

The silicon oxynitride 58 is optional, and in some embodiments may notbe formed.

Referring to FIG. 14, charge-storage material 62 is formed within thegaps 56. The charge-storage material may comprise any suitablecomposition(s); and in some embodiments may comprise charge-trappingmaterials, such as silicon nitride, silicon oxynitride, conductivenanodots, etc. Persons of ordinary skill in the art understand the term“charge-trapping”; and will understand that a “charge trap” may refer toan energy well that can reversibly capture a charge carrier (e.g., anelectron or hole). In alternative embodiments (not shown), thecharge-storage material may be configured as floating gate material(such as, for example, polycrystalline silicon).

The charge-storage material 62 may be formed in the shown configurationwith any suitable methodology. For instance, in some embodiments thecharge-storage material 62 may comprise, consist essentially of, orconsist of silicon nitride, and may be initially formed to at leastpartially fill the opening 24. Excess material 62 may then be removedwith a suitable etch (for instance, an etch utilizing hot phosphoricacid, an etch utilizing oxidation followed by hydrofluoric acidtreatment, etc.) to leave only the material 62 which is confined withinthe gaps 56.

In some embodiments, the charge-storage material 62 may comprise siliconnitride, and the segments of the charge-storage material 62 remainingwithin the gaps 56 may be referred to as silicon nitride segments 64.

Referring to FIG. 15, edges of the silicon nitride segments 64 (FIG. 16)are oxidized to form silicon oxynitride 66 and silicon dioxide 68.Dashed lines 67 are utilized to illustrate approximate boundariesbetween the materials 66 and 68. The material 62 remaining after theformation of the silicon oxynitride 66 and the silicon dioxide 68 may beconsidered to correspond to charge-storage regions (e.g.,charge-trapping regions) 70. The charge-trapping regions 70 have outeredges 71 adjacent the opening 24, inner edges 73 adjacent thecharge-blocking regions 48, and horizontal edges 75 adjacent the ledges50. In the illustrated embodiment, the silicon oxynitride 66 extendsalong the outer edges 71 and along the horizontal edges 75.

In some embodiments, the silicon oxynitride 66 may have a thicknesswithin a range of from about 0.5 nm to about 3 nm, and the silicondioxide 68 may have a thickness within a range of from about 0.5 nm toabout 3 nm.

In the shown embodiment, the charge-storage regions 70 are along, anddirectly adjacent, the silicon dioxide 52 of the charge-blocking regions48 (specifically, the inner edges 73 of the charge storage regions 70are directly against such silicon dioxide 52).

Referring to FIG. 16, the ledges 50 (FIG. 15) are removed to form fourthgaps 72, with the fourth gaps being vertically between thecharge-trapping regions 70. In some embodiments, the material 52 (FIG.15) of the ledges 50 comprises silicon dioxide, and such material isremoved selectively relative to other materials of construction 10 (forinstance, by utilizing a buffered oxide etch).

Referring to FIG. 17, material 74 is formed within the gaps 72. In someembodiments, the material 74 may comprise, consist essentially of, orconsist of silicon nitride; and may be considered to be configured assilicon nitride segments 76. The silicon nitride segments 76 may bereferred to as third silicon nitride segments. In some embodiments, thematerial 18 of the first levels 14 may be referred to as first siliconnitride, and the material 74 may be referred to as second siliconnitride which replaces some of the first silicon nitride.

The silicon nitride segments 74 may be formed with any suitableprocessing. For instance, opening 24 may be at least partially filledwith silicon nitride, and then excess silicon nitride may be removedwith appropriate etching to leave the segments 74 within the gaps 72.

The silicon nitride segments 76 are along the first levels 14, and areadjacent the first material 18 (which in some embodiments may be siliconnitride). In the shown embodiment, the silicon oxynitride 58 is betweenthe silicon nitride segments 76 and the first material 18. In otherembodiments, the silicon oxynitride 58 may be omitted.

Referring to FIG. 18, tunneling materials 78, 80 and 82 are formed alongan outer periphery of the opening 24.

The tunneling materials can function as materials through which chargecarriers tunnel or otherwise pass during programming operations, erasingoperations, etc. In some contexts, one or more of the tunnelingmaterials may be referred to as gate dielectric material, or simply asdielectric material. In the illustrated embodiment, three tunnelingmaterials are utilized. In other embodiments, there may be fewer thanthree tunneling materials; and in yet other embodiments there may bemore than three tunneling materials. In some embodiments, the tunnelingmaterials 78, 80 and 82 may be band-gap engineered to have desiredcharge tunneling properties. The tunneling material 80 iscompositionally different from the materials 78 and 82. The materials 78and 82 may be compositionally different from one another in someembodiments, and may be compositionally the same as one another in otherembodiments. In the illustrated embodiment, the silicon oxynitride 66may correspond to an additional tunneling material. In some embodiments,one or more of the tunneling materials 78, 80 and 82 may be omitted; andinstead the function of such tunneling material may be encompassed withthe silicon oxynitride 66.

In some example embodiments, the tunneling material 80 may comprisesilicon nitride, and the tunneling materials 78 and 82 may comprisesilicon dioxide. In some example embodiments, the tunneling materials 66and 78 may comprise silicon oxynitride and silicon dioxide,respectively; the tunneling material 80 may comprise silicon nitride,and the tunneling material 82 may comprise silicon dioxide.

In some embodiments, the tunneling materials 78, 80 and 82 may bereferred to as first, second and third tunneling materials,respectively.

Channel material 84 is formed within the opening 24 and along thetunneling materials 78, 80 and 82. In the illustrated embodiment, thechannel material 84 is directly against the tunneling material 82. Thechannel material 84 may comprise any suitable appropriately-dopedsemiconductor material(s); and in some embodiments may comprise one ormore of silicon, germanium, III/V semiconductor materials (e.g., galliumphosphide), etc.

In the illustrated embodiment, the channel material 84 lines a peripheryof the opening 24, and insulative material 86 fills a remaining interiorregion of the opening 24. The insulative material 86 may comprise anysuitable composition or combination of compositions, such as, forexample, silicon dioxide. The illustrated configuration of the channelmaterial 84 may be considered to be a hollow channel configuration, inthat the insulative material 86 is provided within a “hollow” in thechannel configuration. In other embodiments, the channel material may beconfigured as a solid pillar.

The channel material 84 extends vertically along the periphery ofopening 24; or, in other words, extends vertically through the stack 12.

Referring to FIG. 19, second openings 88 are formed through the stack12. The second openings 88 extend through the portions of the first andsecond materials 18 and 20.

FIG. 19A shows a top view of a portion of the top level 16 of theillustrated region of construction 10, and illustrates an exampleconfiguration in which the second openings 88 are configured as slits(i.e., trenches).

Referring to FIG. 20, the material 20 (FIG. 19) of the second levels 16is removed to form cavities 90 along the second levels 16. In someembodiments, the material 20 comprises silicon dioxide, and is removedwith a buffered oxide etch.

Referring to FIG. 21, conductive materials 92 and 94 are provided withinthe openings 88 and the cavities 90. The conductive materials 92 and 94may comprise any suitable electrically conductive composition(s), suchas, for example, one or more of various metals (e.g., titanium,tungsten, cobalt, nickel, platinum, ruthenium, etc.), metal-containingcompositions (e.g., metal silicide, metal nitride, metal carbide, etc.),and/or conductively-doped semiconductor materials (e.g.,conductively-doped silicon, conductively-doped germanium, etc.). In someembodiments, the conductive material 92 may comprise, consistessentially of, or consist of titanium nitride; and the conductivematerial 94 may comprise, consist essentially of, or consist oftungsten.

Referring to FIG. 22, conductive materials 92 and 94 are removed fromwithin central regions of openings 88, while leaving the conductivematerials 92 and 94 within the cavities 90.

The conductive materials 92 and 94 remaining within the cavities 90together form conductive regions 96. Although the illustrated conductiveregions comprise two conductive materials, in other embodimentsanalogous conductive regions may comprise only a single conductivematerial, or may comprise more than two conductive materials.

Portions of the conductive regions 96 proximate the charge-blockingregions 48 may correspond to conductive gates 98, and portions of theconductive regions 96 more distal from the charge-blocking regions 48may correspond to wordlines 160. The wordlines are along the levels 16,and accordingly in some embodiments the levels 16 and may be referred toas wordline levels. Such wordline levels may be considered to alternatewith the insulative levels 14 within the stack 12 of FIG. 22.

In some embodiments, the conductive regions 96 may be considered tocomprise first ends 161 and second ends 163 in opposing relation to thefirst ends. The first ends 161 are comprised by the gates 98, and may bereferred to as gate ends; and the second ends 163 are comprised by thewordlines 160, and may be referred to as wordline ends.

Referring to FIG. 23, the first material 18 (FIG. 22), siliconoxynitride 58 (FIG. 22), and material 74 (FIG. 22) are removed withappropriate etching to leave voids 162. In some embodiments, thematerials 18 and 74 comprise, consist essentially of, or consist ofsilicon nitride, and the etching utilized to remove such materialscomprises phosphoric acid as the primary etchant. The phosphoric acidwill etch through the silicon oxynitride 58 slower than the siliconnitride materials; but can etch through the silicon oxynitride,particularly if the silicon oxynitride 58 is less than 10 Å thick. Ifthe silicon oxynitride 58 is problematic, such may be omitted.Alternatively, the etching utilized to form the voids 162 may comprisemultiple stages, with some of the stages being directed toward theremoval of the silicon nitride materials 18 and 74, and another stagebeing directed toward the removal of the silicon oxynitride material 58.

A byproduct that may occur when utilizing phosphoric acid-based etchesto remove silicon nitride is low-density silicon dioxide 164. The term“low-density silicon dioxide” as utilized herein and in the claims thatfollow means silicon dioxide having an etch rate of at least 200Å/minute when utilizing hydrofluoric acid diluted 1:50 in water, at roomtemperature. In some embodiments, the low-density silicon dioxide mayhave an etch rate of at least about 300 Å/minute, at least about 500Å/minute, or even at least about 1000 Å/minute; when utilizinghydrofluoric acid diluted 1:50 in water, at room temperature.Low-density silicon dioxide is highly porous, and accordingly has alower dielectric constant then higher density (less porous) silicondioxide. It can be desired to utilize low dielectric constant materialsas insulative materials between vertically-adjacent wordlines in orderto reduce capacitive coupling between the wordlines.

Some embodiments advantageously utilized the low-density silicon dioxide164 to seal the voids 162, and such is diagrammatically illustrated inFIG. 23. The low-density silicon dioxide 164 produced as a byproduct ofthe etching of the silicon nitride wraps around the wordline ends 163 ofthe conductive regions 96. The low-density silicon dioxide 164 may beconsidered to be configured as insulative liner regions 166 which extendaround the ends 163 of the conductive regions 96. In the embodiment ofFIG. 23, the insulative liner regions 166 merge with one another topinch off ends of the voids 162 (or, in other words, join with oneanother to seal ends of the voids).

The insulative liners 166 do not entirely fill the openings 88 in theembodiment of FIG. 23. Accordingly, remaining portions of the openings88 are filled with additional insulative material 168, as shown in FIG.24. The insulative material 168 may comprise any suitablecomposition(s). In some embodiments, the insulative material 168 willcomprise, consist essentially of, or consist of silicon dioxide; butwill be of a higher density than the low-density silicon dioxide 164.For instance, in some embodiments the insulative material 168 may havean etch rate of less than about 100 Å/minute when utilizing hydrofluoricacid diluted 1:50 in water, at room temperature.

The embodiment of FIG. 23 shows low-density insulative material 164forming insulative regions 166 which merge with one another to seal thevoids 162. In other embodiments, at least some of the insulative regionsmay not merge with one another; and accordingly, open orifices 170 mayremain at ends of the voids (i.e., may extend into the voids), as shownin FIG. 25. However, the insulative material 168 utilized to fill theopenings 88 may also seal the orifices 170, as shown in FIG. 26.

The assemblies 10 of FIGS. 24 and 26 comprise example arrangements ofmemory cells, and in some embodiments may correspond to exampleconfigurations of memory arrays (e.g., NAND memory arrays).Specifically, the conductive gates 98, together with the dielectricbarrier material 38, charge-blocking regions 48, charge-storage regions70, tunneling materials 66, 78, 80 and 82, and channel material 84 maybe incorporated into memory cells 180 a, 180 b and 180 c. Such memorycells may be NAND memory cells in some embodiments. The illustratedmemory cells are vertically-stacked one atop another, and may be part ofa NAND string. The memory cells 180 a, 180 b and 180 c are substantiallyidentical to one another (with the term “substantially identical”meaning identical to within reasonable tolerances of fabrication andmeasurement), and in some embodiments may be referred to as a firstmemory cell, a second memory cell and a third memory cell, respectively.The memory cells 180 a, 180 b and 180 c may be considered to berepresentative of a large number of substantially identical memory cellswhich may be fabricated across a memory array; such as, for example, aNAND memory array analogous to those described above with reference toFIGS. 1-4.

In operation, the charge-storage regions 70 may be configured to storeinformation in the memory cells 180 a, 180 b and 180 c. The value (withthe term “value” representing one bit or multiple bits) of informationstored in an individual memory cell (e.g., 180 a) may be based on theamount of charge (e.g., the number of electrons) stored in acharge-storage region. The amount of charge within an individualcharge-storage region 70 may be controlled (e.g., increased ordecreased), at least in part, based on the value of voltage applied toan associated gate 98, and/or based on the value of voltage applied toan associated channel material 84.

The tunneling materials 66, 78, 80 and 82 together form tunnelingregions 184 of the memory cells 180 a, 180 b and 180 c. Such tunnelingregions may be configured to allow desired tunneling (e.g.,transportation) of charge (e.g., electrons) between the charge-storageregions 70 and the channel material 84. The tunneling regions 184 may beconfigured (i.e., engineered) to achieve a selected criterion, such as,for example, but not limited to, an equivalent oxide thickness (EOT).The EOT quantifies the electrical properties of the tunneling region(e.g., capacitance) in terms of a representative physical thickness. Forexample, EOT may be defined as the thickness of a theoretical silicondioxide layer that would be required to have the same capacitancedensity as a given dielectric (e.g., tunneling region 184), ignoringleakage current and reliability considerations.

The charge-blocking regions 48 are adjacent to the charge-storageregions 70, and may provide a mechanism to block charge from flowingfrom the charge-storage regions 70 to the associated gates 98. Thedielectric barrier material 38 is provided between the charge-blockingregions 48 and the associated gates 98, and may be utilized to inhibitback-tunneling of electrons from the gates 98 toward the charge-storageregions 70. In some embodiments, the dielectric barrier material 38 maybe considered to form dielectric barrier regions within the memory cells180 a, 180 b and 180 c.

In some embodiments, the channel material 84 may be considered to be achannel configured to conduct current. The channel includes a firstchannel portion 190 which is incorporated into the first memory cell 180a, a second channel portion 192 which is incorporated into the secondmemory cell 180 b, and a third channel portion 194 which is incorporatedinto the third memory cell 180 c.

The gate 98 which is incorporated into the memory cell 180 a may bereferred to as a first gate, the gate 98 which is incorporated into thesecond memory cell 180 b may be referred to as a second gate, and thegate 98 which is incorporated into the third memory cell 180 c may bereferred to as a third gate.

The charge-blocking region 48 and charge-storage region 70 within amemory cell may be together considered to be a memory cell structure196. The memory cell structure 196 within the first memory cell 180 amay be referred to as a first memory cell structure, the memory cellstructure 196 within the second memory cell 180 b may be referred to asa second memory cell structure, and the memory cell structure 196 withinthe third memory cell 180 c may be referred to as a third memory cellstructure. The dielectric barrier material 38 forms dielectric barrierregions within the first, second and third memory cells 180 a, 180 b and180 c. Such dielectric barrier regions may be considered to be part ofthe memory cell structures 196 in some embodiments, and may beconsidered to be separate from the memory cell structures 196 in otherembodiments. The dielectric barrier region within the first memory cell180 a may be referred to as a first dielectric barrier region, thedielectric barrier region within the second memory cell 180 b may bereferred to as a second dielectric barrier region, and the dielectricbarrier region within the third memory cell 180 c may be referred to asa third dielectric barrier region.

The charge-blocking regions 48 within the memory cell structures 196 arebetween the charge-storage regions 70 and the gates 98. In theillustrated embodiments of FIGS. 24 and 26, the silicon oxynitride 54within the charge-blocking regions 48 may be considered to have twoopposing lateral sides 193 and 195. The silicon dioxide 52 of thecharge-blocking regions 48 is along one of the opposing lateral sides(the side 193), and the other of the opposing lateral sides (the side195) is directly adjacent the dielectric barrier material 38 in theshown embodiment.

The gate 98 of the first memory cell 180 a is vertically spaced from thegate 98 of the second memory cell 180 b. One of the voids 162 isvertically between the vertically-spaced gates 98 of the first andsecond memory cells 180 a and 180 b; and such void is labeled as 162 ain FIGS. 24 and 26 to enable the void to be distinguished from the othervoids.

The void 162 a has a region 187 between the vertically-neighboring gatesof the memory cells 180 a and 180 b, and has another region 189 betweenthe vertically-neighboring memory cell structures 196 of the memorycells 180 a and 180 b. The other voids 162 have similar regions 187 and189. Accordingly, the voids 162 can provide electrical isolation betweenvertically-neighboring memory cell structures 196, and can also provideelectrical isolation between vertically-neighboring conductive gates 98.In the shown embodiment of FIGS. 24 and 26, at least portions of theconductive regions 96 of the gates 98 are spaced from the voids 162 bylow-density silicon dioxide 164, and the charge-storage regions 70 arespaced from the voids by liners 199 corresponding to regions of thesilicon oxynitride 66. The dielectric barrier materials 38 are directlyagainst the voids 162.

In some embodiments, the stacks 12 of FIGS. 24 and 26 may be consideredto comprise alternating insulative levels 14 and wordline levels 16. Thechannel material 84 extends vertically along the stack 12, and the gates98 are along the wordline levels and spaced from the channel material bythe tunneling materials (66, 76, 80 and 82), the memory cell structures196, and the dielectric barrier material 38.

The charge-storage regions (i.e., charge-storage structures) 70 arevertically-spaced from one another by intervening regions of the voids162 along the insulative levels 14. The vertical separation of thecharge-storage regions 70 from one another may alleviate or preventcharge leakage between neighboring charge-storage regions within acommon NAND string; and may mitigate coupling of charge-storage regionswith other components (e.g., neighboring charge-storage regions, controlgate, channel, tunnel oxide, etc.). Such may enable substantialimprovements relative to conventional NAND configurations having acontinuous charge-storage structure extending along all of the memorycells of a NAND string. Example improvements may include one or more ofimproved endurance, improvement in read/write budget, improvement inquick charge gain, improvement in quick charge loss, reducedcell-to-cell capacitive coupling, cycling, etc.

Isolation of vertically-adjacent charge-storage regions from one another(as compared to conventional configurations having continuouscharge-storage regions) may alleviate or prevent charge leakage andcharge coupling between neighboring charge-storage regions, and otherneighboring components within a common NAND string.

Provision of voids (e.g., air gaps) between vertically-adjacentwordlines may reduce capacitive capacitance between the wordlines, andmay improve resistor-capacitor (RC) properties of the wordlines. Suchmay reduce programming delay and/or provide other advantages as comparedto other configurations.

The assemblies and structures discussed above may be utilized withinintegrated circuits (with the term “integrated circuit” meaning anelectronic circuit supported by a semiconductor substrate); and may beincorporated into electronic systems. Such electronic systems may beused in, for example, memory modules, device drivers, power modules,communication modems, processor modules, and application-specificmodules, and may include multilayer, multichip modules. The electronicsystems may be any of a broad range of systems, such as, for example,cameras, wireless devices, displays, chip sets, set top boxes, games,lighting, vehicles, clocks, televisions, cell phones, personalcomputers, automobiles, industrial control systems, aircraft, etc.

Unless specified otherwise, the various materials, substances,compositions, etc. described herein may be formed with any suitablemethodologies, either now known or yet to be developed, including, forexample, atomic layer deposition (ALD), chemical vapor deposition (CVD),physical vapor deposition (PVD), etc.

The terms “dielectric” and “insulative” may be utilized to describematerials having insulative electrical properties. The terms areconsidered synonymous in this disclosure. The utilization of the term“dielectric” in some instances, and the term “insulative” (or“electrically insulative”) in other instances, may be to providelanguage variation within this disclosure to simplify antecedent basiswithin the claims that follow, and is not utilized to indicate anysignificant chemical or electrical differences.

The particular orientation of the various embodiments in the drawings isfor illustrative purposes only, and the embodiments may be rotatedrelative to the shown orientations in some applications. Thedescriptions provided herein, and the claims that follow, pertain to anystructures that have the described relationships between variousfeatures, regardless of whether the structures are in the particularorientation of the drawings, or are rotated relative to suchorientation.

The cross-sectional views of the accompanying illustrations only showfeatures within the planes of the cross-sections, and do not showmaterials behind the planes of the cross-sections, unless indicatedotherwise, in order to simplify the drawings.

When a structure is referred to above as being “on”, “adjacent” or“against” another structure, it can be directly on the other structureor intervening structures may also be present. In contrast, when astructure is referred to as being “directly on”, “directly adjacent” or“directly against” another structure, there are no interveningstructures present.

Structures (e.g., layers, materials, etc.) may be referred to as“extending vertically” to indicate that the structures generally extendupwardly from an underlying base (e.g., substrate). Thevertically-extending structures may extend substantially orthogonallyrelative to an upper surface of the base, or not.

Some embodiments include a memory array which has a vertical stack ofalternating insulative levels and wordline levels. Channel materialextends vertically along the stack. Conductive segments are along thewordline levels. Individual of the conductive segments have, along across-section, first and second ends in opposing relation to oneanother. The conductive segments include gates and wordlines adjacentthe gates. The wordlines encompass the second ends and the gatesencompass the first ends. Memory cell structures are along the wordlinelevels and are located between the gates and the channel material. Thememory cell structures include charge-storage regions andcharge-blocking regions. The charge-blocking regions are between thecharge-storage regions and the gates. Voids are along the insulativelevels and are between vertically-neighboring of the memory cellstructures. Insulative liner regions are along the wordline levels andextend around the second ends of the conductive segments. The insulativeliner regions contain low density silicon dioxide.

Some embodiments include an assembly having a channel to conductcurrent. The channel includes a first channel portion and a secondchannel portion under the first channel portion. A first memory cellstructure is located between a first gate and the first channel portion.The first memory cell structure includes a first charge-storage regionand a first charge-blocking region. The first charge-blocking region islocated between the first charge-storage region and the first gate. Thefirst charge-blocking region comprises silicon oxynitride, and the firstcharge-storage region comprises silicon nitride. A second memory cellstructure is under the first memory cell structure and is locatedbetween a second gate and the second channel portion. The second memorycell structure includes a second charge-storage region and a secondcharge-blocking region. The second charge-blocking region is locatedbetween the second charge-storage region and the second gate. The secondcharge-blocking region comprises silicon oxynitride, and the secondcharge-storage region comprises silicon nitride. A void is locatedbetween the first and second gates, and between the first and secondmemory cell structures. The first gate comprises conductive materialover the void and spaced from the void by low-density silicon dioxide.The second gate comprises conductive material under the void and spacedfrom the void by low-density silicon dioxide. A first liner is betweenthe silicon nitride of the first charge-storage region and the void. Asecond liner is between the silicon nitride of the first charge-storageregion and the void.

Some embodiments include a method of forming an assembly. A firstopening is formed through a stack of alternating first and secondlevels. The first levels contain silicon nitride, and the second levelscontain silicon dioxide. Some of the silicon dioxide of the secondlevels is replaced with memory cell structures while leaving remainingportions of the silicon dioxide of the second levels. The memory cellstructures include charge-storage regions adjacent charge-blockingregions. Vertically-extending tunneling material is formed within thefirst opening. The tunneling material extends along the charge-storageregions of the memory cell structures. Channel material is formed withinthe first opening and adjacent the tunneling material. A second openingis formed through the stack. The second opening extends through theremaining portions of the silicon dioxide of the second levels, andextends through the silicon nitride of the first levels. The remainingportions of the silicon dioxide of the second levels are removed to formcavities along the second opening. Conductive regions are formed withinthe cavities. The silicon nitride of the first levels is removed to formvoids between the conductive regions.

Some embodiments include a method of forming an assembly. A firstopening is formed through a stack of alternating first and secondlevels. The first levels comprise first material, and the second levelscomprise second material. The first material of the first levels isrecessed along the first opening to form first gaps. The first gaps arevertically between segments of the second levels. Spacing structures areformed within the first gaps. The second material of the second levelsis recessed along the first opening to form second gaps and to leaveremaining portions of the second material along the second gaps. Thesecond gaps are vertically between segments of the spacing structures.Individual of the second gaps each have an upper peripheral surface, alower peripheral surface and an inner peripheral surface. Liners ofdielectric barrier material are formed to extend along the upperperipheral surface, the inner peripheral surface and the lowerperipheral surface of each of the second gaps, and to narrow the secondgaps. First silicon nitride segments are formed within the narrowedsecond gaps and along the second levels. Vertically-neighboring of thefirst silicon nitride segments are vertically-spaced from one another byintervening regions which include the spacing structures. Oxidizingconditions are utilized to oxidize the silicon nitride segments and tooxidize the spacing structures. The oxidized silicon nitride segmentsare charge-blocking regions. The oxidized spacing structures are ledges.Third gaps are vertically between the ledges. Second silicon nitridesegments are formed within the third gaps and along the charge-blockingregions. Edges of the second silicon nitride segments are oxidized. Theoxidized edges include edges along the first opening, and include edgesalong the ledges. Remaining regions of the silicon nitride segmentswhich are not oxidized are charge-trapping regions. The ledges areremoved to leave fourth gaps. The fourth gaps are vertically between thecharge-trapping regions. Third silicon nitride segments are formedwithin the fourth gaps. The third silicon nitride segments are along thefirst levels and are adjacent remaining portions of the first material.Vertically-extending tunneling material is formed within the firstopening. The tunneling material extends along edges of the third siliconnitride segments and along the charge-trapping regions. Channel materialis formed within the first opening and adjacent the tunneling material.A second opening is formed through the stack. The second opening extendsthrough the remaining portions of the first material, and through theremaining portions of the second material. The remaining portions of thesecond material of the second levels are removed to form cavities alongthe second levels. Conductive regions are formed within the cavities.The remaining portions of the first material and the third siliconnitride segments of the first levels are removed to form voids along thesecond opening.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

I/We claim:
 1. A method of forming an assembly, comprising: forming afirst opening through a stack of alternating first and second levels;the first levels comprising silicon nitride, and the second levelscomprising silicon dioxide; replacing some of the silicon dioxide of thesecond levels with memory cell structures while leaving remainingportions of the silicon dioxide of the second levels; the memory cellstructures comprising charge-storage regions adjacent charge-blockingregions; forming vertically-extending tunneling material within thefirst opening, the tunneling material extending along the charge-storageregions of the memory cell structures; forming channel material withinthe first opening and adjacent the tunneling material; forming a secondopening through the stack; the second opening extending through theremaining portions of the silicon dioxide of the second levels, andthrough the silicon nitride of the first levels; removing the remainingportions of the silicon dioxide of the second levels to form cavitiesalong the second opening; forming conductive regions within thecavities; and removing the silicon nitride of the first levels to formvoids between the conductive regions.
 2. The method of claim 1 whereinthe silicon nitride of the first levels is first silicon nitride, andfurther comprising replacing some of the first silicon nitride of thefirst levels with second silicon nitride after forming the first openingand prior to forming the second opening; wherein the removing of thesilicon nitride to form the voids comprises removing the first andsecond silicon nitride; and wherein the voids have regions betweenvertically-neighboring of the gates and have regions betweenvertically-neighboring of the memory cell structures.
 3. The method ofclaim 2 wherein the removing of the first and second silicon nitrideforms insulative liner regions extending around the ends of theconductive regions adjacent the second opening; the insulative linerregions comprising low density silicon dioxide.
 4. The method of claim 3wherein vertically-neighboring of the insulative liner regions join withone another to seal ends of the voids.
 5. The method of claim 4 whereinthe insulative liner regions partially fill the second opening; andfurther comprising filling a remainder of the second opening withsilicon dioxide having a higher density than the silicon dioxide of theinsulative liner regions.
 6. The method of claim 3 whereinvertically-neighboring of the insulative liner regions arevertically-spaced from one another along ends of the voids to leaveorifices extending into the ends of the voids; wherein the insulativeliner regions partially fill the second opening; and further comprisingfilling the orifices and a remainder of the second opening with silicondioxide having a higher density than the silicon dioxide of theinsulative liner regions.
 7. A method of forming an assembly,comprising: forming a first opening through a stack of alternating firstand second levels; the first levels comprising first material, and thesecond levels comprising second material; recessing the first materialof the first levels along the first opening to form first gaps; thefirst gaps being vertically between segments of the second levels;forming spacing structures within the first gaps; recessing the secondmaterial of the second levels along the first opening to form secondgaps and to leave remaining portions of the second material along thesecond gaps; the second gaps being vertically between segments of thespacing structures; individual of the second gaps each having an upperperipheral surface, a lower peripheral surface and an inner peripheralsurface; forming liners of dielectric barrier material to extend alongthe upper peripheral surface, the inner peripheral surface and the lowerperipheral surface of each of the second gaps, and to narrow the secondgaps; forming first silicon nitride segments within the narrowed secondgaps and along the second levels; vertically-neighboring of the firstsilicon nitride segments being vertically-spaced from one another byintervening regions which include the spacing structures; utilizingoxidizing conditions to oxidize the silicon nitride segments and tooxidize the spacing structures; the oxidized silicon nitride segmentsbeing charge-blocking regions; the oxidized spacing structures beingledges; third gaps being vertically between the ledges; forming secondsilicon nitride segments within the third gaps and along thecharge-blocking regions; oxidizing edges of the second silicon nitridesegments; the oxidized edges including edges along the first opening,and including edges along the ledges; remaining regions of the siliconnitride segments which are not oxidized being charge-trapping regions;removing the ledges to leave fourth gaps; the fourth gaps beingvertically between the charge-trapping regions; forming third siliconnitride segments within the fourth gaps; the third silicon nitridesegments being along the first levels and being adjacent remainingportions of the first material; forming vertically-extending tunnelingmaterial within the first opening; the tunneling material extendingalong edges of the third silicon nitride segments and along thecharge-trapping regions; forming channel material within the firstopening and adjacent the tunneling material; forming a second openingthrough the stack; the second opening extending through the remainingportions of the first material, and through the remaining portions ofthe second material; removing the remaining portions of the secondmaterial of the second levels to form cavities along the second levels;forming conductive regions within the cavities; and removing theremaining portions of the first material and the third silicon nitridesegments of the first levels to form voids along the second opening. 8.The method of claim 7 wherein the removing of the remaining portions ofthe first material and the third silicon nitride segments of the firstlevels forms insulative liner regions extending around the ends of theconductive regions adjacent the second opening; the insulative linerregions comprising low density silicon dioxide.
 9. The method of claim 8wherein vertically-neighboring of the insulative liner regions join withone another to seal ends of the voids.
 10. The method of claim 9 whereinthe insulative liner regions partially fill the second opening; andfurther comprising filling a remainder of the second opening withsilicon dioxide having a higher density than the silicon dioxide of theinsulative liner regions.
 11. The method of claim 8 whereinvertically-neighboring of the insulative liner regions arevertically-spaced from one another along ends of the voids to leaveorifices extending into the ends of the voids; wherein the insulativeliner regions partially fill the second opening; and further comprisingfilling the orifices and a remainder of the second opening with silicondioxide having a higher density than the silicon dioxide of theinsulative liner regions.
 12. The method of claim 7 wherein the formingof the liners of dielectric barrier material comprises: forming a layerof the dielectric barrier material to extend conformally along theperipheral surfaces of the second gaps and along outer edges of thespacing structures; forming a mass of silicon nitride along the layer ofthe dielectric barrier material; the mass of silicon nitride extendingwithin the gaps and along the outer edges of the spacing structures;removing some of the mass of silicon nitride to form the first siliconnitride segments from the mass of silicon nitride; and after removingsaid some of the mass of silicon nitride; removing the dielectricmaterial from along the edges of the spacing structures while leavingthe liners of the dielectric barrier material.
 13. The method of claim 7wherein the first material comprises silicon nitride; and wherein thesecond material comprises silicon dioxide.
 14. The method of claim 13wherein the second levels are vertically thicker than the first levels.15. The method of claim 7 wherein the recessing of the second materialto form the second gaps exposes regions of the first material along backportions of the second gaps.
 16. The method of claim 7 wherein thespacing structures comprise polycrystalline silicon; and wherein theoxidizing conditions oxidize induce more expansion along thepolycrystalline silicon than along the silicon nitride of the siliconnitride segments.
 17. The method of claim 16 wherein the oxidizingconditions induce at least about double the expansion along thepolycrystalline silicon than along the silicon nitride.
 18. The methodof claim 16 wherein the oxidizing conditions induce substantially noexpansion along the silicon nitride.
 19. The method of claim 7 whereinthe spacing structures comprise polycrystalline silicon; and wherein theoxidizing conditions oxidize the polycrystalline silicon faster than thesilicon nitride segments.
 20. The method of claim 19 wherein the firstmaterial comprises silicon nitride; wherein the ledges have front edgesalong the first opening, and have back edges along the first material;wherein the oxidizing conditions oxidize the regions of the firstmaterial along the back edges of the ledges to form silicon oxynitrideliners; wherein the third silicon nitride segments are formed directlyagainst the silicon oxynitride liners; and wherein the formation of thevoids includes removal of the silicon oxynitride liners.
 21. The methodof claim 19 wherein the oxidizing conditions utilize a temperature of atleast about 700° C.
 22. The method of claim 21 wherein the oxidizingconditions utilize remote plasma.
 23. The method of claim 21 wherein theoxidizing conditions utilize steam.
 24. The method of claim 19 whereinthe charge-blocking regions comprise silicon oxynitride and silicondioxide.